1. Field of the Invention
The subject matter disclosed generally relates to the field of hard disk drives.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads write and read information by magnetizing and sensing the magnetic fields of the disk surfaces. Each head is attached to a flexure beam to create a subassembly commonly referred to as a head gimbal assembly (“HGA”). The HGA's are attached to an actuator arm that has a voice coil coupled to a magnet assembly. The voice coil and magnet assembly create a voice coil motor that can pivot the actuator arm and move the heads across the disks.
Information is typically stored within annular tracks that extend across each surface of a disk. The voice coil motor can move the heads to different track locations to access data stored onto the disk surfaces. Each track is typically divided into a plurality of adjacent sectors. Each sector may have one or more data fields. Each data field has a series of magnetic transitions that are decoded into binary data. The spacing between transitions define the bit density of the disk drive. It is generally desirable to provide a high areal density to increase the overall storage capacity of the drive. The areal density is defined as the product of the tracks per inch (“TPI”) and bits per inch (“BPI”) density of the disk.
The track density, also referred to as tracks per inch (“TPI”) is limited by the width of the heads and the tolerances associated with the head widths. The head width tolerance can be up to 10% of the nominal design track pitch. Some drives create a variable TPI format to compensate for different head widths. Present techniques to determine the optimal TPI per head include a bit error rate technique which is a time consuming method that also requires a read channel optimization process. It would be desirable to determine an optimal TPI per head that does not require as much time as techniques of the prior art.